Treatment of creosote



Jan. 25, 1944. R. ALLOTT El AL TREATMENT OF CREOSOTE Filed July 13. 1940 INVENTOR LEONARD RALLOTT EUGENE P. MlLLER 2 BY I Mp ATTORNEYS Patented Jan. 25, 1944 Leonard R. Allott and Eugene P.

0010., assignors to The Colorado Miller, Pueblo, Fuel and Iron Corporation, Denver, 0010., a corporation of Colorado Application July 13, 1940, Serial 345,424 Claims. (01. 196-146) 1 This invention relates to the treatment of coal tar creosote and particularly to the treatment of creosote derived from coal by the direct process in which the creosote is subjected to the temperatures prevailing in' distillation for only a short period of time,'of the order of four to five minutes.

' Coal tar creosote, particularlythat derived by the direct process, tends to deteriorate upon ageing. In order to be saleable as first grade material, it must fulfill certain rigid specifications, and frequently coal tar creosote which fulfilled these specifications at the time it was produced, fails to conform after a period of several weeks of storage or ageing. Thus, coal tar creosote which originally had a coke residue con-, tent below the usual tolerable limit of 2.00% may deteriorate upon storage until its coke residue content exceeds this limit, in which case the creosote is no longer saleable, at least as first grade material. That this tendency toward deterioration of coal tar creosote in storage is a recognized one is evidenced by the requirements of some users that the creosote shall meet specifications at the time of use, as well asat the time of shipment from the producing plant.

As a result of our investigations, We have discovered that coal tar creosote may be prevented from deteriorating and in fact actually improved in quality by'maintaining it in contact with a liquid aqueous body (such as a pool of water which may or may not contain dissolved material) at relatively low temperatures (such as those normally encountered in stored creosote) for a considerable period of time and out of contact with oxidizing influences. The more thorough and intimate is the contact between the creosote and the water, the greater is the improvement of the character of the creosote. Thus, deterioration of coal tar creosote can-be prevented completely and the grade of the creosote slowly improved by storing it in a tank at atmospheric temperatures under a layer of Water. However, more rapid improvement in grade maybe ob-. tained by passing water through the body of the creosote into the overlying water layer, thereby increasing the surface of contact between the water and the creosote. ,7

The action of the aqueous body appears to be twofold in that it acts as a seal and protects the creosote from oxidizing influences, such as air, and also may leach from the creosote certain harmful substances which, if allowed to remain, ten'd'tobring about excessive deterioration of the creosote. These and other features of our invention will be understood more readily inthe light of the following detailed description of our presently preferred practices, taken in conjunction with the accompanying single figure which illustrates one form of apparatus adapted for storing or treating the creosote in accordance with our invention.

Coal tar creosote must fulfill rigid requirements for specific gravity, water content, percentages distilled at various temperatures, residue after distillation, specific gravity of various fractions distilled, coke residue, tar acid content, flash point, etc. An effort has been made to standard-' ize' these specifications, but some variation is found for specifications in various grades of creosote and also in the specifications set up by various consumers. However, practically; all specifications, regardless of grade of creosote or ofthe particular consumer, require that the coke residue of the creosote shall not exceed 2.00%. Especially when the creosote as produced closely approaches the upper limit of 2% coke residue, this specifica tion is likely to be exceeded during a period of storage or shipment, so that the creosote becomes unsaleable as first quality oil. Other characteristics of the creosote, as exemplified by the foregoing items of specification, may also suffer unfavorable changes if the creosote is allowed to stand for a considerable time prior to use, and our invention contemplates preventing deterioration of the creosote with respect to these characteristics and also contemplates improving creosote with respect to these characteristics.

Creosote ordinarily is stored in large cylindrical tanks. gallons in a single tank is common practice. An easy method for practicing the invention with creosote stored in such tanks is'to introduce a layer of several inches of water into the tank. The water is substantially immiscible with the. creosote and has a lower specific gravity so that it floats as a layer on' the creosote in the tank and thus seals it from the air. At the same time, solution of undesirable ingredients of the creosote takes place at the interface between the water and the creosote and these ingredients when once dissolved in the water no longerexert their harmful influence upon the creosote. A more rapid removal of the undesirable ingredients and greater improvement in the character of the creosote. may be obtained by increasing the surface of 00117, tact between the water and the creosote in the.

tank. This may be done conveniently by introducing the water in a relatively finely divided. state below the surface of the creosote and per Storage of quantities exceeding 100,000

mitting it to rise upwardly through the creosote to the overlying water seal. In its progress through the body of creosote the water tends to leach out the undesirable ingredients and brings ing creosote through an inlet line [3 which enters the tank adjacent the top of the creosote pool, creosote being withdrawn from the bottom of the tank through a gooseneck IA. The gooseneck about a rapid and permanent improvement in the 5 is so constructed that its top is at approximately character of the creosote and particularly in its the same level as the upper surface of the creosote coke residue content. pool s o that ac onstant and predetermined level The imisretemehtin the character of creosote otc'reosote'is maintained within theetank. Water obtainedin the practice of our inventiondeconis introduced into the tank through a vertical trasted with the deterioration which is exper i 19 pipe l6 which is connected with a perforated enced with similar material when it is permitted hollow g n n the bottom f t t Th to stand under ordinary conditions exposedto the ring may conveniently be made of pipe. The perair. As an example of heretoiore customary iorationsin the ring are small so that the water practice in the storage of "creosote, a body of e ntersin minutestreams and gives a maximum creosote amounting to 150,0601ga1 1on fws' er- "contact surfacewith the surrounding creosote. mitted to stand in a tank ata temperature of The Water is substantially immiscible With the about 25 C. but in contact with air at its upper creosote and rises upw rd y th ou h the p0 1 surface for a period of four weeks. As the .rolth reo i t the o yin Water lay from whi h lowing analysis shows, the material in the Joet they be Ve O through an Out t pipe ginning of the storage period was of high grade connected to the side of the tank. and had a coke residue content well below .the it Will be observed that in the apparatus a limit of 2%. However, duringstorage the matecountercurrent flow of creosote andlwa e maybe rial deteriorated,substantially with the result that meintaihed, if desire 0 the Qt nd, if i it no longer fulfilled specifications and was unis unnece t 'pur he 1 50% ext s e y saleable as first-grade material. an rapidly, end it s me l n e sary 11 P e- Tabze No I vent its deterioration, or bring about a slow improvement in grade, no flow of Water or creosote through the tank need be maintained, in which Sample Original: case the tank is merely a storage reservoir in which the creosote isprotected and slowly'ben es ecific mvs L 52 5 i tedhy the overlying w rl gerceng griven oggi si%ation to 21 :0; 4.5a :2.7- The degree of improvement which results from P333211; (13323 fie diittiitififi 535?? 8: @316 t???) h msre s ra o c eo und a protective Per cent driven qfidis tillation to 355 o. 80.5 7st water layer is well illustrated by the comparative 25 333Ei fi itiiiiti ff fiiz:3:31:111:1:1-5:: i131 th resu t iv in e I eQi s D e No. II- Thi improvementis, however, brought about relative- L 3! w y, and more rapid improvement is oba-iiti titiiitwffii iifiitttisttt firifi a r d in h cheater of coal tar vby weeks in a'tank under conditidns precisely similar mgamg of Contact ibeFwgen the to those described above, ircebtthat thecrosote -t and the1re9stebeynd that prmded by was covered by a are or'seei of water about 2 .meillterface and inches thick and amounting 1569,00 ganonsjiourn r m l er. m be brought about. ing this'three' week e ioayas the following Table vamus types apparatus. 9 Scmbbmg No. II shows, there was an ii'ri'riroi me'ritih' the WW??? and but qrdmanil? 1t 1S character of th'creosot'e. Thus, the'original coke essay to 61.11pm suchpqmplex t fi and the residue content of2.'05%- was reduced during apparatus Illustrated the figuire Wm gwe excel storage to 1.82% after threeweeks treatment lent r'esplts' In mstence mustrated by the so that the material was" brought" into a; first figgfism the Table "11,000 grade condition 1 I lons of water were passed upwardly through an s I J y r 9 1100 gallon batch of creosotein a period of three Table No.11 hours. 7 Originally, the coke residue content of the creosote was 2.09%. This was reduced to S Orig After After 3 during the three hours contact period.

pl ma} 2weeks 3weeks storage storage Table III ti iitt dlitir"Easement; 2 3 mp ori inal ggig P e r ceEi'EVfibli iiiiiadbdi' 2L9 2L9 m tgfigi gi 'g' gg {13 gg 5M 5 622 Per cent distilled at 235 0. 15.8 17. i 85.1 84.0 as 1 3% 8 23-3 t2;332%fiiittfltffiiii::::::::: 3:35 it i2 3;gggggsggtzggggeg greg &3, Flash point, 171.0 189.0 Referring now to the drawing, it will be observed that the apparatus comprisesalar ec lindrical tank In which is disposed vertical l y. The In the trqatmgnt exemplified by Table 9 tank preferably should be of large diameter in the apparatus correspondmg to that f m the relationto its height so as to provide a large figure was employed The Water-Was immers surfa e for contact between the water and the a fin l g d S ms i h n he 9991 9? th creosote. A body of creosote II is maintained 9 39 9 1 W5 thfiF h t ll h 2 e over yin within" thetank; and it is overlain by a layer of W te? al ye water L2 which seals the creosote from the air. It i e ob e e h t in d n to improve If desired, a relatively continuous flow of creosote e with respect to coke residue the distillate may be maintained through the pool by introduc tion residue" of the creosote was also decreased by the treatment. Moreover, the flash point of the creosote was raised and the float test results were improved. All of these are desirable changes in grade and indicate an improvement in the general quality of the creosote which is obtained when the water is percolated through the creosote.

While we do not subscribe to any particular theory as to how the water brings about the improvement in the creosote, we are inclined to believe, as indicated hereinbefore, that it acts in a twofold manner. In the first place, the water layer acts as a seal and protects the creosote from oxidizing influences. In the second place, the water in contact with the creosote apparently leaches out undesirable ingredients which have a tendency to bring about an increase in the coke residue content. Analysis of water which has remained in contact with creosote in accordance with our invention shows a substantial content of both ammonia and phenol. It is probable that these substances or chemical combinations thereof, such as the comparatively simple ammonium phenate, or one or more complex phenol amines exert a deleterious influence if allowed to remain in the creosote. In any event, the removal of these ingredients from the creosote not only prevents its deterioration but actually brings about an improvement in its grade.

In the process of our invention a greater degree of beneficiation results when the creosote treated is that derived by flash distillation in a direct recovery process. In such a process, coal tar re mains at distillation temperature for a very short time, probably not in excess of four to five minutes. In contrast, tar distilled in an old type batch still remains in the still and in a heated condition for a fairly long time, from six to fortyeight hours being required for the preparation of a batch of creosote by this means. It is probable that during the longer heating in the batch still method, many of the compounds which otherwise would form coke residue in the creo sote during the storage thereof are formed in the still and remain with the tar. On the other hand, in a flash distillation process the formation of these compounds is not completed in the still, but tends to take place slowly in the creosote during storage. The formation of these compounds, with a consequent increase in coke residue content of the creosote, is promoted by heat or by oxidizing influences. Consequently, in the practice of our invention, it is necessary to maintain the creosote at relatively low temperatures, preferably at temperatures as low as 20 C. and in no case at temperatures high enough that a substantial proportion of the creosote is vaporized. Moreover, mere treatment with water without sealing the creosote from oxidizing influences ordinarily is not beneficial.

As indicated hereinbefore, ordinary water with or without dissolved mineral salts, etc., is an adequate treating agent. However, various chemicals including anti-oxidants may be included in the water, if desired. In this connection, it may be observed that the phenol leached from the creosote by the water apparently exerts an antioxidant action when present in the latter.

We claim:

, 1. In the treatment of coal tar creosote containing ammonia and phenol, the improvement which comprises passing water upwardly through a body of the creosote while the latter is in a liquid condition and at a relatively low temperature and out of contact with oxidizing influences until a substantial proportion of the ammonia and phenol has been leached out of the creosote and dissolved in the water and the coke residue content of the creosote is substantially reduced.

2. In the treatment of coal tar creosote containing ammonia and phenol, the improvement which comprises passing water upwardly through a body of the creosote in liquid condition and at a relatively low temperature and out of contact with oxidizing influences and so leaching out of the creosote and dissolving into the water a substantial proportion of the ammonia and phenol, the water being passed upwardly through the creosote until the coke residue content of the creosote is substantially reduced, the water being passed into a layer of water overlying the body of creosote and in contact therewith.

3. In the treatment of coal tar creosote containing ammonia and phenol, the improvement which comprises passing the creosote in liquid condition and at a relatively low temperature in countercurrent contact with water while maintaining the creosote out of contact with oxidizing influences, the creosote being passed in countercurrent contact with the water until the coke residue of the creosote is substantially reduced and a substantial proportion of the ammonia and phenol has been leached out of the creosote.

4. In the treatment of coal tar creosote containing ammonia and phenol, the improvement which comprises passing water in a liquid condition and at a relatively low temperature through a body of creosote maintained at a relatively low temperature until a substantial proportion of the ammonia and phenol has been leached out of the creosote and the coke residue content is substantially reduced, the creosote being protected from the action of oxidizing influences during the treatment with the water.

5. In the treatment of coal tar creosote containing ammonia and phenol, the improvement which comprises passing a fine stream of water upwardly through a body of the creosote maintained at a relatively low temperature and out of contact with oxidizing influences until a substantial proportion of the phenol and ammonia has been leached out of the creosote into the water and the coke residue content of the creosote is substantially reduced, the water being passed through the creosote into an overlying layer of water.

LEONARD R. ALLOTT. EUGENE P. MILLER. 

